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Aspects of the chemistry of some phosphorus halides and pseudohalides

Platt, A. W. G. (1980) Aspects of the chemistry of some phosphorus halides and pseudohalides. Doctoral thesis, Durham University.



The preparation of pseudohalogeno derivatives of the simple phosphorus(V) species PC1(_4)(^+), PC1(_5) and PC1(_6)(^-) has been attempted. In the case of the tetrachlorophosphonium ion only azido-derivatives are observable in normal organic solvents, cyano and thiocyanato derivatives being more stable in liquid halogen media. Isolation of these compounds was not possible. Molecular derivatives based on PC1(_5) seem to be particularly unstable and are only readily observable under forcing conditions for cyanide. The derivatives of the hexachlorophosphate ion are all observable, PX(_6)(^-) being readily formed for X = N(_3), NCS, NCO and OCN although these and the intermediate species are all unstable. The series of cyanides PC1(_6-n)(CN)(_n)(^-) (0 < n < 3) have been isolated as solids and fully characterised, and the presence of isomers for n = 2 and 3 has been clearly established. The six-coordinate fluorochlorophosphates PF(_3)Cl(_3)(^-), PF(_2)C1(_4)(^-) and PFC1(_5)(^-) have been isolated as pure tetraalkylammonium salts and the reactions of these anions studied with respect to substitution by pseudohalides. The observation of PF(_6-n)X(_n)(^-) (X = pseudohalogen) has been carried out by ligand exchange between PF(_6)(^-) and PX(_6)(^-) (where known) or PX(_3) and attempts have been made to isolate compounds, where feasible, by other reactions such as the addition of pseudohalide ions to PF(_5).The use of pairwise interactions has proved invaluable in assigning formulae in the tetrahedral systems, and in both assigning formulae and identifying specific isomers in many of the six-coordinate systems. The substitution patterns in the six-coordinate systems can be rationalised in terms of a simple steric model, or on the basis of ligand field theory for the cyanides. Other six-coordinate systems have been studied with respect to substitution by azide and several new species have been identified.

Item Type:Thesis (Doctoral)
Award:Doctor of Philosophy
Thesis Date:1980
Copyright:Copyright of this thesis is held by the author
Deposited On:18 Sep 2013 09:23

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